A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels.

Huajun Li,Haiqing Li,Guohua Wu,Baoliang Wang,Zhiyao Huang,Haifeng Ji

doi:10.3390/s16020159

Abstract

Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers’ works.

Highlights

In the past decades, the studies and industrial applications of gas-liquid two-phase flow in small-channel systems, such as chemical reactors, heat exchangers, refrigeration processes and micro-evaporators etc., have become a significant area [1,2,3]
A photodiode array sensor is used to obtain the signals of the exit laser
Aathe photodiode array sensor is used used to obtain obtain the signals of the the exit exit laser

Summary

Introduction

The studies and industrial applications of gas-liquid two-phase flow in small-channel systems, such as chemical reactors, heat exchangers, refrigeration processes and micro-evaporators etc., have become a significant area [1,2,3]. Void fraction is an important parameter of the two-phase flow. Its on-line measurement is of great importance for the heat and mass transfer efficiency, the estimation of pressure drop, the process control and the measurement of other parameters of the two-phase flow [4,5,6,7,8,9]. The conventional measurement methods cannot fulfill the growing requirements of the industrial applications and the mechanism studies of the two-phase flow [1,2,3,4,5,6,7,8,9].

Objectives

Methods

Discussion

Conclusion